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      A New Method of Color Doppler Perfusion Measurement via Dynamic Sonographic Signal Quantification in Renal Parenchyma

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          Abstract

          Objective: Perfusion quantification of tissues is an important goal to evaluate the state of blood supply of an organ. We developed a method to quantify tissue perfusion via color Doppler signal quantification from sonographic videos and applied this to describe renal parenchymal perfusion in healthy kidneys. Method: Color Doppler sonographic videos of renal perfusion from both kidneys of 87 healthy children (age 2 weeks to 16 years) were recorded under defined conditions. Perfusion data (color hue, color area) were measured in a standardized region of interest automatically. Signal intensity was calculated as whole ROIs (regions of interest) mean flow velocity (cm/s) encoded by color Doppler signals during one full heart cycle. Results: Normal signal intensity values are: 1.86 cm/s in the region encompassing central 50% of the renal cortex and 0.56 cm/s in the peripheral 50% of the renal cortex. These differences are significant. Signal intensity of both kidneys did not differ. Conclusion: Signal intensity of cortical tissue in healthy kidneys was quantified noninvasively from color Doppler signal data in an easily accomplishable manner with new measurement software. Normal values for this technique have been calculated. Possible further applications might be all situations, where perfusion changes could be expected like inflammation, renal insufficiency, vascular diseases and tumors.

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          Most cited references 5

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          Quantification of renal blood flow with contrast-enhanced ultrasound.

          The goal of this study was to determine the ability of contrast-enhanced ultrasound (CEU) to quantify renal tissue perfusion. The kinetics of tracers used to assess renal perfusion are often complicated by countercurrent exchange, tubular transport or glomerular filtration. We hypothesized that, because gas-filled microbubbles are pure intravascular tracers with a rheology similar to that of red blood cells, CEU could be used to quantify renal tissue perfusion. During a continuous venous infusion of microbubbles (SonoVue), regional renal perfusion was quantified in nine dogs using CEU by destroying microbubbles and measuring their tissue replenishment with intermittent harmonic imaging. Both renal blood volume fraction and microbubble velocity were derived from pulsing-interval versus video-intensity plots. The product of the two was used to calculate renal nutrient blood flow. Renal arterial blood flow was independently measured with ultrasonic flow probes placed directly on the renal artery and was increased using dopamine and decreased by placement of a renal artery stenosis. An excellent correlation was found between cortical nutrient blood flow using microbubbles and ultrasonic flow probe-derived renal blood flow (r = 0.82, p < 0.001) over a wide range (2.5 fold) of flows. Ultrasound examination during microbubble infusion can be used to quantify total organ as well as regional nutrient blood flow to the kidney.
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            Contrast superharmonic imaging: a feasibility study.

            Harmonic imaging provided significant improvement in image quality by taking advantage of the scattered second harmonic (2H) component from contrast bubbles. However, differentiation between contrast and tissue (usually termed contrast-to-tissue ratio, CTR) is sometimes cumbersome and this is mainly due to tissue contamination. We have previously demonstrated, using simulations and in vitro measurements, that CTR increases as a function of the order of the harmonic number. A new contrast imaging method based on the detection of the higher harmonics was developed and termed superharmonic (SH). This technique has been shown to be more sensitive to contrast by increasing the signal from contrast and suppressing that from tissue (high CTR). The purpose of this study was to determine the clinical feasibility and usefulness of SH in patients using a commercially available contrast agent (SonoVue(R)) for quantification of myocardial perfusion. A total of 10 patients with various cardiac diseases were assessed. Apical four-chamber views were acquired using SH in triggered mode before and after contrast injection. The superharmonic was performed with a newly developed probe transmitting at 0.8 MHz with a mechanical index of 0.2. Myocardial perfusion was determined visually and analyzed quantitatively using radiofrequency (RF) processing from different regions of interest. The results showed that, before contrast injection, SH was totally blinded to tissue and no superharmonic components were generated in the image view. After administration of SonoVue(R), myocardial opacification was visualized by SH after contrast entered the myocardium. An increase of more than 15 dB in the myocardial bubbles echo compared to tissue echo was measured. In addition, the technique was used to visualize myocardial perfusion after myocardial septal ablation for hypertrophic cardiomyopathy. The clinical results showed the ability of contrast SH imaging in differentiating low and normal perfusion areas, demonstrating the high sensitivity and specificity of the technique.
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              Quantification of regional myocardial perfusion using semiautomated translation-free analysis of contrast-enhanced power modulation images.

              Quantitative analysis of myocardial perfusion is currently based on manual tracing and frame-by-frame realignment of regions of interest. We developed a technique for semiautomated identification of myocardial regions from power modulation images as a potential tool for quantification of myocardial contrast enhancement. This approach was tested in 13 anesthetized pigs during continuous intravenous infusion of contrast at baseline, left anterior descending coronary artery occlusion, and reperfusion. Regional pixel intensity was calculated for each consecutive end-systolic frame after a high-energy ultrasound impulse, and fitted with an exponential function. Perfusion defects caused by occlusion of left anterior descending coronary artery were confirmed by a significant decrease in both postimpulse steady-state intensity and the initial rate of contrast replenishment (P <.05), which were reversed with reperfusion. Automated measurements of myocardial intensity correlated highly with conventional manual tracing (r = 0.90 to 0.97), and resulted in improved signal-to-noise ratios. This technique allows translation-free quantification of regional myocardial perfusion, without the need for manual tracing.
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                Author and article information

                Journal
                NEP
                Nephron Physiol
                10.1159/issn.1660-2137
                Nephron Physiology
                S. Karger AG
                1660-2137
                2004
                April 2004
                30 April 2004
                : 96
                : 4
                : p99-p104
                Affiliations
                aKinderklinik am Städtischen Klinikum ‘St. Georg’, und bSektion Mathematik, Universität Leipzig, Leipzig, Deutschland
                Article
                77380 Nephron Physiol 2004;96:p99–p104
                10.1159/000077380
                15122055
                © 2004 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                Figures: 3, Tables: 1, References: 11, Pages: 1
                Product
                Self URI (application/pdf): https://www.karger.com/Article/Pdf/77380
                Categories
                Original Paper

                Cardiovascular Medicine, Nephrology

                Color Doppler sonography, Tissue perfusion, Healthy children

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